This invention pertains to downhole equipment utilized for hydrocarbon wells and is particularly directed to reducing the amount of rig time and the associated expense with drilling a hydrocarbon well.
A conventional hydrocarbon well has a plurality of concentric casing strings extending from the ground surface to the subsurface hydrocarbon reservoir, with the outermost string having the largest diameter and being the shortest in length, with each inner string having a smaller diameter and a longer length. The outermost pipe, the conductor pipe, is installed as part of site preparation and will be present when the drilling rig moves onto the location.
Once located at the site, the drilling rig drills to the next casing point, which is a predetermined depth set below freshwater bearing zones, or incompetent or difficult strata such as sloughing clay or gravel zones. Once the first casing point is reached, the surface casing is run into the well, and cemented in place, usually by pumping cement down through the inside of the casing, and continuing to pump until the cement comes out of the bottom of the casing and circulates up into the annulus between the open hole and the outside of the surface casing. The last joint of surface casing will typically be held in tension until the cement reaches a predetermined strength, at which time the blowout preventer is removed and a wellhead housing attached to the surface casing.
Drilling thereafter continues, until the next casing point is reached, at which time a smaller string of casing is run into the well through the larger diameter surface casing. Depending upon the integrity of the drilled strata and the anticipated depth of the well, the casing point may extend all of the way to the production zone and production casing installed. Alternatively, one or more intermediate strings of casing may be concentrically installed within the surface casing.
The production casing is cemented in place. After all of the cement has been pumped into place, the casing string is held stationary while the cement sets up. Thereafter, a slip-type casing hanger is placed around the top joint of the production casing, which is typically landed within the wellhead housing.
In the current method, the equipment utilized generally requires that a drilling rig be present as cement sets, and requires a blow out preventer be changed in and out as the casing installation procedure goes forward. The presently disclosed apparatus and method of use reduce the rig time associated with completing a well and it reduces the times a blow out preventer must be made up and nippled down.